1. Field of the Invention
The invention relates to external rear view mirrors for motor vehicles that allows a driver to observe objects located in a blind spot of the vehicle.
2. Description of the Related Art
The blind spot (or zone) of a motor vehicle is an area around the vehicle that cannot be directly observed by a driver with ease. The blind spots of most significance to a driver of a vehicle are the areas located adjacent to the rear quadrants of the vehicle. Objects in these areas may not be visible to a driver using a conventional rear view mirror (interior or exterior). There is therefore an inherent danger that a blind spot accident may occur when changing lanes or attempting to overtake another vehicle. The simplest solution to prevent an accident of this type occurring is for the driver to physically turn their head and to look directly behind into the blind spot. This is cumbersome and requires the driver to take their eyes off the road in front of them which presents additional dangers.
A solution to the above problem is to increase the field of view of the exterior (side) rear view mirror to enable viewing of the blind spot. A spotter (or blind spot) mirror may be provided to achieve this additional field of view. A spotter mirror is usually a convex mirror that may be fitted as an aftermarket add-on to the exterior rear view mirror. In other forms, it may be a separate mirror component that is mounted into the mirror assembly or it may be formed integrally with the exterior rear view mirror. The spotter mirror has a field of view encompassing the vehicle's blind spot such that objects located in the blind spot become observable to the driver when they view the reflection provided by the spotter mirror.
Although using a spotter mirror alleviates the problem to some extent, often it is desirable to provide the driver with further blind spot indication and to direct their attention towards the spotter mirror. This may be achieved by a blind spot indicator which may take the form of a visual stimulus such as a light or illuminated symbol or alternatively an audio sound. This additional stimulus immediately alerts the driver viewing the exterior mirror that an object is present in the blind zone and prompts them to pay particular attention to the spotter mirror, thereby drawing their attention to an object in the vehicle's blind zone. Alternatively, the driver may notice the indicator in their peripheral vision which will then prompt them to look at the spotter mirror.
A problem with known blind spot indicators, particularly illuminated markers and lighting displays is that they are often located in a region of the actual mirror surface such that when operable they partly reduce or obscure the driver's visible field of view. These blind spot indicators for external rear view mirrors are also visible to other road users which may create a source of distraction or interference.
For example, U.S. Pat. No. 6,919,796 (Boddy et al) discloses an exterior side mirror having a primary reflective mirror, a spotter mirror and a blind spot indicator. The blind spot indicator is located either on the spotter mirror or around the periphery of the spotter mirror. These locations are problematic as the field of view of the spotter mirror is either compromised by the blind spot indicator or in the case of the indicator (signalling light) around the periphery of the spotter mirror; the light would be easily visible to other road users and may become a source of distraction of interference.
An alternative construction is disclosed in US Patent Application No. 2005/0174645 (Boddy et al) in which a spotter mirror is integrally formed with the primary mirror to form an external rear view mirror assembly. A series of lighting elements is inserted around a portion of the circumference of the spotter mirror to draw the driver's attention to the spotter mirror when an object is detected in the blind spot of the vehicle. A blind spot indicator configured in this way would partially obscure the field of view of the spotter mirror and would also be readily viewable by other road users when activated.
An object of the present invention is to ameliorate one or more of the above described difficulties or at least provide a useful alternative to arrangements of the type discussed above.
Other advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, a preferred embodiment of the present invention is disclosed.